This invention relates to an improved method of manufacturing a rod end joint having a rod and one or more ball sections arranged at an end or ends of the rod.
Japanese Patent Laid-open No. 63-190923 teaches a method of manufacturing a ball joint. According to this method, a ball is welded to each of the longitudinal ends of a rod having a length smaller than that of the final product and then the distance between the centers of the balls at the ends of the rod is adjusted by elongating the rod so as to produce a rod end joint.
According to this known method, however, it is not possible to accurately adjust the distance between the centers of the balls at the ends of the rod, because adjustment of the distance between the centers of the balls depends solely on press technique.
Moreover, according to this technique, since a cylindrical straight portion of the rod is slenderized by rotating, a diameter of the rod is not uniform and the rod has an uneven strength.